The present invention relates to the stabilization of drugs including antibiotics and food supplements. Particularly, it concerns the granulation of Efrotomycin, milbemycins, tylosin derivatives, e.g., A.I.V. (3-acetyl-4"-isovaleryl tylosin), antibiotics B-5050 and tetrahydro-B-5050, Ivermectin, mocimycin, goldinomycin and the like in alginic acid and magnesium hydroxide. It has been found that the granules so obtained exhibit unexpectedly enhanced stability and can be incorporated into various formulations without substantial decomposition. When the drugs or food supplements are administered to animals, the formulations include animal feed, pellets or feed premix.
Efrotomycin (FR-02A) is a new antibiotic which also exhibits growth-promoting activity. It is effective against both gram-positive and gram-negative bacteria and accordingly is useful in the treatment of a broad spectrum of infections in animals. Efrotomycin is disclosed in U.S. Pat. No. 4,024,251 issued May 17, 1977 to Maiese and Wax. The antibiotic is isolated from the fermentation broth of Streptomyces lactamfuran by solvent extraction and is believed to have the molecular structure as follows: ##STR1##
The physical properties of Efrotomycin (FR-02A) are summarized as follows: Elemental analysis:
C 60.98% PA1 H 7.60% PA1 N 2.60% PA1 max. 233 nm: E.sub.1 cm.sup.1% =320 PA1 max. 328 nm: E.sub.1 cm.sup.1% =180 PA1 max. 325 nm: E.sub.1 cm.sup.1% =317 PA1 max. 230 nm: E.sub.1 cm.sup.1% =554 PA1 max. 219 nm: E.sub.1 cm.sup.1% =556 PA1 Broad Band at: 3400 PA1 Strong bands at: 1640, 1460, 1380, 1080, 1020 PA1 Prominent bands at: 1550, 1505, 1240, 1195, 940, 860, 720, 620. PA1 (1) Ivermectin: a potent antiparasitic agent disclosed in U.S. Pat. No. 4,199,569. PA1 (2) Milbemycins (antibiotics B-41): antibiotics characterized in U.S. Pat. Nos. 4,144,352; 3,950,360; and British Patent Specification No. 2,056,986. PA1 (3) Tylosin and derivatives, e.g., A.I.V.: antibiotics disclosed in U.S. Pat. No. 4,092,473. A.I.V. is the 3-acetyl-4"-isovaleryl derivative (R.sub.1 is acetyl and R is isovaleryl in formula I) of tylosin. PA1 (4) Antibiotics B-5050 and tetrahydro-B-5050: disclosed in U.S. Pat. No. 3,853,842. PA1 (5) Mocimycin dihydromocimycin, antibacterial agents disclosed in U.S. Pat. Nos. 3,927,211 and 4,062,948. PA1 (6) Goldinomycin disclosed in U.S. Pat. No. 3,657,421. PA1 (1) develop a granulation method which will produce sufficiently stable granules for inclusion of unstable drugs or food supplements in animal feeds, or other human and animal formulations; PA1 (2) provide a novel stable formula or composition containing one or more of the granulated drugs or food supplements which is resistant to heat, humidity, and other adverse conditions; and PA1 (3) apply the formula and process equally to other unstable human or animal drugs or food supplements for inclusion in feed, tablets or capsules or other suitable formulations. PA1 (a) 0.1 to 70 parts by weight of an active compound especially Efrotomycin, A.I.V. or Ivermectin; PA1 (b) 10 to 80 parts by weight of a polysaccharide gelling agent especially guar gums (natural or synthetic), tragacanth, acacia, alginic acid and its salts and derivatives, starch, locust bean gum, agar-agar, xanthan gum, karaya gum, gum ghatti and carrageenan or a mixture thereof; and PA1 (c) 10 to 80 parts by weight of a metal salt especially an oxide, a hydroxide, a carbonate or a silicate of aluminum, calcium or magnesium, for example, magnesium hydroxide. PA1 (a) 2-40 parts by weight of an active compound; PA1 (b) 20-50 parts by weight of alginic acid; or calcium alginate or a combination thereof in the ratio 2-3 parts of alginic acid to 2-3 parts of calcium alginate; and PA1 (c) 20-85 parts by weight of a metal oxide or hydroxide. PA1 (a) 5-35 parts by weight of an active compound; PA1 (b) 15-50 parts by weight of alginic acid; and PA1 (c) 20-80 parts by weight of magnesium hydroxide.
The corresponding empirical formula C.sub.59 H.sub.90 N.sub.2 O.sub.21 is consistent with monohydrated FR-02A. This is in agreement with a molecular weight of about 1168 of the sodium complex of FR-02A determined by field desorption mass spectrometry. Further mass spectroscopic study of FR-02A determined the molecular weight 1144 for the uncomplexed compound corresponding to the empirical formula C.sub.59 H.sub.88 N.sub.2 O.sub.20.
FR-02A as the ammonium salt is soluble in alcohol and chloroform. It is moderately soluble in water at pH 7.0 or higher. A U.V. spectrum of the ammonium salt in water showed:
After further purification FR-02A in the free acid has the following U.V. spectrum in methanol--0.05M phosphate buffer pH 6.85 (20:80):
Specific optical rotation of FR-02A sodium salt is [.alpha.].sub.D.sup.20 -56.6.+-.0.5 (C=1, MeOH).
The nuclear magnetic resonance spectrum of antibiotic FR-02A was obtained at 100 MHz with CDCl.sub.3 as the solvent and tetramethylsilane (TMS) as the internal standard. Representative features of the spectrum were Doublets at 1.21(3H), 1.31(3H), 1.74(3H), 4.63(1H), 4.87(1H), 5.94(1H) and 7.32(1H) ppm. Overlapping signals of 4 other C-methyl groups centered at about 0.94 ppm; Singlets at 1.65(3H), 2.02(3H), 3.15(3H), 3.42(3H), 3.45(3H), 3.54(3H), and 3.58(3H) ppm.
The infrared absorption spectrum of antibiotic FR-02A in a Nujol mull exhibits characteristic absorption at the following wave lengths expressed in reciprocal centimeters:
Further characteristics of FR-02A as well as the process for isolating the antibiotic are described in U.S. Pat. No. 4,024,251 and are herein incorporated by reference.
Efrotomycin is found to be unstable at elevated temperatures especially in the presence of moisture and feed components. However, in administering Efrotomycin to animals, it is most convenient and economic to include the antibiotic-growth promotor agent in premixes for animal feeds. Usually a premix is blended into animal feeds followed by injection of steam resulting in a final temperature of 85.degree.-100.degree. C. The mixing process takes about 2-15 minutes. The agglomerates may be either cooled and dried to produce a mash feed or extruded to give pelleted feed. In other words, Efrotomycin must be stabilized first before it can be incorporated into animal feeds.
Accordingly, it is desirable to develop a method of formulation for the stabilization of Efrotomycin to enable the inclusion thereof in animal feed.
One of the commonly used methods of formulation for stabilization is granulation because of ease, efficiency and consequently lower cost. Methods described in the literature include granulation with specific inorganic materials (U.S. Pat. No. 3,627,885, Dec. 14, 1971) or with starch (U.S. Pat. No. 4,048,268, Sept. 13, 1977). Neither of these techniques were suitable for Efrotomycin.
Granulation with inorganic salts, particularly those of magnesium did result in some stabilization but unexpected synergistic improvement occurred when polysaccharides were incorporated into the formulation as can be seen from table 1.
TABLE 1 ______________________________________ The effect of the addition of polysaccharide gelling agents to magnesium hydroxide on the stability of efrotomycin stored in animal feed at 50.degree. C., (all contain 5% efrotomycin and magnesium hydroxide:gum in the weight ratio 1:1). Magnesium Storage % of initial Polysaccharides hydroxide time remaining ______________________________________ -- -- 17 days 12 -- present 25 days 56 Guar gum (anionic) present 28 days 71 Guar gum (nonionic) present 28 days 79 Guar gum (cationic) present 28 days 55 Tragacanth present 28 days 68 Acacia present 28 days 81 Alginic acid present 35 days 100 Calcium alginate present 56 days 82 Sodium alginate present 30 days 69 Maize starch present 14 days 90 Locust Bean gum present 14 days 83 Agar-agar present 14 days 80 ______________________________________
For efrotomycin incorporation of alginic acid gives the best stabilization although all the polysaccharides including those listed in Table 1 and xanthan gum, karaya gum, gum ghatti, and carrageenan offer significant protection.
In case of efrotomycin, the ratio of alginic acid to magnesium hydroxide is important as can be seen in table 2.
TABLE 2 ______________________________________ The effect of alginic acid - magnesium hydroxide ratio on the stability of efrotomycin stored in animal feed at 50.degree. C. (all contain 10% efrotomycin). % of initial % Magnesium % Alginic remaining after hydroxide w/w acid w/w 4 months storage ______________________________________ 90 -- 26 75 15 73 60 30 91 45 45 93 30 60 100 15 75 75 -- 90 37 ______________________________________
It should be noted that the method of the present invention is not limited to Efrotomycin. Any other unstable animal drugs or food supplements may be incorporated into animal feeds or other formulations including human drug formulations according to the formula and process described herein. Particularly, for example, the following drugs:
The physical characterization, the biological activity as well as the isolation of the above-identified drugs are herein incorporated by reference.
It has been found that these drugs may also be stabilized by granulation with a polysaccharide gelling agent especially alginic acid blended with an inorganic salt, particularly metal oxides or hydroxides such as magnesium hydroxide. The granules may be incorporated into feed, tablets, capsules, or other formulations.